Vol. 9, Special Issue 10, Part W (2025)

Bitter gourd production faces severe constraints due to mosaic disease caused by a viral complex comprising Cucumber Mosaic Virus (CMV), Tomato Leaf Curl New Delhi Virus (ToLCNDV), and Papaya Ringspot Virus (PRSV). This study sought to identify and characterize naturally resistant genotypes for integration into breeding programs aimed at developing virus-resistant varieties. Thirty bitter gourd genotypes were evaluated after artificial inoculation via wedge grafting, an efficient technique for simultaneous transmission of multiple viruses. Disease response was quantified using the Vulnerability Index (VI) and a 0-5 symptom severity scale. Three landraces—Lodhi local, Udayagiri local, and Therthari local—demonstrated high resistance (VI = 0%) with no observable symptoms. In contrast, commercial cultivars such as Priyanka and Preethi showed high susceptibility (VI up to 86.67%). Biochemical profiling reve aled that resistant genotypes exhibited elevated baseline and induced activity of defense enzymes—peroxidase (PER), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL)—compared to susceptible lines. These findings were further validated using Double Antibody Sandwich ELISA (DAS-ELISA), which confirmed the absence of viral antigens in the highly resistant genotypes, as indicated by low absorbance values. The identified resistant genotypes represent a valuable genetic resource for developing resilient bitter gourd varieties, which is essential for sustainable disease management and improving crop yield.